feat: move entirely to built in vim.lsp.config

[mehalter]

📑 Description

This is pretty far out, but gives a placeholder for future development and shows the progress getting made in the background. This moves entirely to using vim.lsp.config and vim.lsp.enable for powering LSP features in Neovim.

Required Before Merging

• Completion of nvim-lspconfig migration to vim.lsp.config: Missing legacy configs neovim/nvim-lspconfig#3705
• mason-lspconfig v2 release
• Neovim v0.12 for inclusion of workspace_required option in vim.lsp.config

ℹ Additional Information

• AstroNvim branch updated to use this version
• config table has been refactored to be a general API for vim.lsp.config which includes moving default capabilities and flags to config = { ["*"] = { capabilities = {}, flags = {} } }, users can still do their configuration in ~/.config/nvim/lsp/<server_name>.lua
• The default on_attach behavior is moved to an autocommand on LspAttach event
  • The configuration of the default on_attach function extension simply adds onto this autocommand and allows easily modifying it/reverting things that are not desired.
  • mappings/autocommands/commands options are still left and are simply part of the default on_attach autocommand
• Default configuration of capabilities and flags is simply calling vim.lsp.config("*", { capabilities = M.config.capabilities, flags = M.config.flags })
• require("astrolsp").lsp_opts(server_name) has been removed. The configuration can simply be retrieved with vim.lsp.config[server_name]
• Remove hack for allowing users to extend mason-lspconfig at runtime. This is not necessary as Mason packages will manage their own mappings to nvim-lspconfig server names